Silicone network polymers are attracting attention as optoelectronic materials, ceramic precursors and so on.
Heretofore, a linear polysilane containing Si--Si linkages in the backbone chain has been synthesized from a dichlorosilane as the starting compound by heating the starting compound together with sodium metal at a temperature not below 100.degree. C. A silicon network polymer, however, cannot be synthesized by subjecting a trichlorosilane as such to the same conditions as above. Thus, in order to synthesize a silicon network polymer, it is necessary to modify not only the starting compound but also the reaction conditions. Therefore, a synthetic method employing a sonication technique in combination with a very strong reducing system, e.g. a sodium metal-potassium alloy system (J. Am. Chem. Soc. 110 (1988) 234) and a method using an alkali metal, e.g. sodium metal, and an appropriate auxiliary agent such as 12-crown-4 (Macromolecules 1990, 23, 3423-3426) have been proposed. However, these methods are disadvantageous in that they do not provide for molecular weight control and that the use of alkali in a large amount presents a major safety problem in commercial production runs. Thus, neither of the methods can be utilized for production on a commercial scale.
As a technology for synthesizing linear polysilanes, several processes involving electrode reactions which permit molecular weight control and are safe have been reported (J. Chem. Soc. Chem. Commun., 1990, 1160, Electrochem. Acta, 35, 1867 (1990), Denki Kagaku Oyobi Kogyo Butsuri Kagaku 59, 5, 421 (1991), JP Kokai H-3-104893, etc.). However, none of the above-cited literature consider production of a silicon network polymer and, for that matter, none provide information on how such a silicon network polymer could ever be obtained.
Therefore, the development of an electrode reaction technology for producing silicone network polymers has been awaited.